The present invention relates to a shredder having a document feeding function, in which a number of documents stacked on a document feeding tray are delivered, at least, one sheet by one sheet to a pair of shredding blades so as to be shredded by the shredding blades.
Conventionally, in shredders including a feed roller for feeding documents stacked on a document feeding tray and means for preventing many of the documents from being transported at a time, the documents are fed, at least, one sheet by one sheet through separation of the documents by the feed roller and are delivered from a transport path to a pair of shredding blades so as to be shredded by the shredding blades. In the known shredders, documents to be shredded under conditions exceeding strength and a maximum rotational load of the shredding blades are prevented from being transported to the shredding blades by decreasing curvature and size of the transport path. Namely, generally, as thickness of documents increases, stiffness of the documents increases. Hence, the thick documents cannot follow the small curvature and thus, stop in the course of the transport path.
In the known shredders of the above described arrangement, in the case where documents incapable of being shredded by the known shredders are fed into the known shredders, transport of the documents is stopped. However, if this state of stop of transport of the documents is continued, wear of the feed roller is caused, thereby resulting in deterioration of document feeding capability of the feed roller.
Meanwhile, in prior art shredders for automatically shredding a number of documents, the operator may sometimes leave the shredders. Thus, such a phenomenon may take place in which a long time period elapses before the operator becomes aware of stoppage of transport of the documents. As a result, the feed roller is subjected, for a long time, to wear due to its drive, thus resulting in damage to the feed roller.